Most silencers designed for use with centerfire pistol-caliber host firearms incorporate into their design parts such as a piston and return coil spring that are collectively called a “Nielsen Device,” Linear Inertial Decoupler, or an Assured Semi-Automatic Performance System (“A.S.A.P.” System). Such Nielsen Devices enable the weight of the silencer body to move away or decouple from the barrel of the firearm so that the weight of the silencer does not hamper tilting of the breech end of the firearm barrel, which tilting is generally inherent in the modified “Browning” design of most centerfire host pistols found in today's marketplace. The return spring re-positions the silencer body after each shot, to reset the silencer for subsequent shots. However, when using such a silencer on a host firearm with a fixed, non-moving barrel, the movement of the silencer has been seen as unnecessary since the barrel stays substantially static. Thus, to eliminate such unnecessary movement, accessory spacers have been used to replace the return spring of the Nielsen Device so that the silencer may be used on a host firearm with a fixed, non-moving barrel. These spacers typically include pieces of steel or aluminum tube that approximate the length of the spring as it would sit inside the silencer body. A shortcoming of this spacer design that has been found is that when the silencer is of a type configured for use on a tilting barrel host firearm, vibrations from firing can cause the return spring retainer cap to inadvertently unscrew from the body of the silencer during use, which can lead to a decrease in accuracy and reliability of the host firearm.